Lifting apparatus and sheet storage apparatus

ABSTRACT

A lifting apparatus includes a motor, circular support members, power transmission members, guide mechanisms, and electromagnets. The circular support members provide tensile forces to wires connected to a load. The power transmission members rotate around the rotation axis Ax as a center of rotation by driving force of the motor. The guide mechanisms support the circular support members so as to enable the circular support members to slide in a predetermined ranges along a radial direction of the rotation axis, respectively. The electromagnets forcibly arrange the circular support members using electromagnetic force at a position that the center axes of the circular support members agree with the rotation axis in the predetermined ranges.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application relates to and claims priority rights from Japanese Patent Application No. 2022-019226, filed on Feb. 10, 2022, the entire disclosures of which are hereby incorporated by reference herein.

BACKGROUND 1. Field of the Present Disclosure

The present disclosure relates to a lifting apparatus and a sheet storage apparatus.

2. Description of the Related Art

An image forming apparatus such as printer or multi function peripheral includes a sheet storage apparatus that stores sheets such as printing paper sheets. For example, the sheet storage apparatus includes a sheet loading plate on which sheets are loaded and a lifting apparatus that causes the sheet loading plate to move up and down. Such a lifting apparatus performs pulling-in and pulling-out of a wire connected to the sheet loading plate using a driving force of a motor and thereby causes the sheet loading plate to move up and down.

In the aforementioned lifting apparatus, a tensile force to the wire occurs due to gravity applied to a load such as sheets and the sheet loading plate, and therefore, a backstop mechanism such as worm gear is installed such that the wire does not move due to the tensile force and the load does not move down when the motor is in a power off status (i.e. when the motor does not generate torque). However, installing such a backstop mechanism causes a complicated power train mechanism from the motor to the wire, and some space is required to arrange the backstop mechanism.

SUMMARY

A lifting apparatus according to an aspect of the present disclosure includes a motor, a first circular support member, a first power transmission member, a first guide mechanism, a first electromagnet, a second circular support member, a second power transmission member, a second guide mechanism, and a second electromagnet. The first circular support member is configured to provide tensile force to a first wire connected to a load. The first power transmission member is configured to rotate around a rotation axis as a center of rotation by driving force of the motor. The first guide mechanism is configured to support the first circular support member so as to enable the first circular support member to slide in a predetermined first range along a radial direction of the rotation axis. The first electromagnet is configured to forcibly arrange the first circular support member using electromagnetic force at a position that a center axis of the first circular support member agrees with the rotation axis in the predetermined first range. The second circular support member is configured to provide tensile force to a second wire connected to the load. The second power transmission member is configured to rotate around the rotation axis as a center of rotation by driving force of the motor. The second guide mechanism is configured to support the second circular support member so as to enable the second circular support member to slide in a predetermined second range along a radial direction of the rotation axis. The second electromagnet is configured to forcibly arrange the second circular support member using electromagnetic force at a position that a center axis of the second circular support member agrees with the rotation axis in the predetermined second range.

A sheet storage apparatus according to an aspect of the present disclosure includes the aforementioned lifting apparatus and a sheet loading unit configured to be caused to move up and down by the lifting apparatus.

These and other objects, features and advantages of the present disclosure will become more apparent upon reading of the following detailed description along with the accompanied drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a diagram that indicates a configuration of a sheet storage apparatus in embodiments of the present disclosure;

FIG. 2 shows an exploded perspective view diagram that indicates a configuration of a lifting apparatus in Embodiment 1;

FIG. 3 shows a perspective view diagram that indicates a configuration of the lifting apparatus in Embodiment 1 (1/2);

FIG. 4 shows a perspective view diagram that indicates a configuration of the lifting apparatus in Embodiment 1 (2/2);

FIG. 5 shows a diagram that explains an arrangement of a circular support member in the lifting apparatus shown in FIGS. 2 to 4 (1/2);

FIG. 6 shows a diagram that explains an arrangement of a circular support member in the lifting apparatus shown in FIGS. 2 to 4 (2/2);

FIG. 7 shows a diagram that explains an operation (wire pulling-out operation) of the lifting apparatus shown in FIGS. 2 to 4 ;

FIG. 8 shows a diagram that explains a maximum deviation length of the wire in the operation of the lifting apparatus shown in FIGS. 6 and 7 ;

FIG. 9 shows a diagram that explains an operation (wire pulling-in operation) of the lifting apparatus shown in FIGS. 2 to 4 ;

FIG. 10 shows a diagram that explains an operation in a power off status of the lifting apparatus shown in FIGS. 2 to 4 when a direction of the power transmission member is in a predetermined first angle range;

FIG. 11 shows a diagram that explains a maximum deviation length of the wire in an operation at a power off status of the lifting apparatus shown in FIG. 10 ;

FIG. 12 shows a diagram that explains an operation in a power off status of the lifting apparatus shown in FIGS. 2 to 4 when a direction of the power transmission member is in a predetermined second angle range;

FIG. 13 shows a front view diagram that indicates a configuration of a lifting apparatus in Embodiment 2; and

FIG. 14 shows a diagram that explains an operation in a power off status of the lifting apparatus in Embodiment 2.

DETAILED DESCRIPTION

Hereinafter, embodiments according to an aspect of the present disclosure will be explained with reference to drawings.

Embodiment 1

FIG. 1 shows a diagram that indicates a configuration of a sheet storage apparatus in embodiments of the present disclosure.

The sheet storage apparatus shown in FIG. 1 includes a lifting apparatus 1, a controller 2, sheet storage units 3-1 and 3-2, and wires 4-1 and 4-2.

The lifting apparatus 1 is an apparatus that performs pulling-in and pulling-out of the two wires 4-1 and 4-2 and thereby moves a load up and down.

The controller 2 electrically controls the lifting apparatus 1. For example, the controller 2 is a computer that executes a control program, an ASIC (Application Specific Integrated Circuit) and/or the like. The controller 2 causes the lifting apparatus 1 to perform moving up and/or moving down of a load in accordance with a user operation, a status of the load, or the like.

The sheet storage units 3-1 and 3-2 include sheet loading units 3 a and pulleys 3 b, respectively. An end of the wire 4-1 is connected to the sheet loading unit 3 a of the sheet storage unit 3-1, the wire 4-1 is suspended on the pulley 3 b, and the other end of the wire 4-1 is connected to the lifting apparatus 1. An end of the wire 4-2 is connected to the sheet loading unit 3 a of the sheet storage unit 3-2, the wire 4-2 is suspended on the pulley 3 b, and the other end of the wire 4-2 is connected to the lifting apparatus 1.

The lifting apparatus 1 performs pulling-in and pulling out of the wires 4-1 and 4-2 and thereby moves up and down the sheet loading units 3 a in the sheet storage units 3-1 and 3-2. Here, the aforementioned load is the two sheet storage units 3-1 and 3-2 (the sheet loading units 3 a). Alternatively, the lifting apparatus 1 may perform moving up and down a single sheet loading unit 3 a in a single sheet storage unit by performing pulling-in and pulling-out of the two wires 4-1 and 4-2.

FIG. 2 shows an exploded perspective view diagram that indicates a configuration of a lifting apparatus in Embodiment 1. FIGS. 3 and 4 show perspective view diagrams that indicate a configuration of the lifting apparatus in Embodiment 1.

For example, as shown in FIGS. 2 to 4 , the lifting apparatus 1 includes a motor 11, power transmission members 12-1 and 12-2, electromagnets 13-1 and 13-2, and circular support members 14-1 and 14-2.

Further, this lifting apparatus 1 includes (a) a pulley 10 a, (b) a center axis 10 b that connects and fixes the power transmission members 12-1 and 12-2 to the pulley 10 a, (c) a support member 10 c that supports the center axis 10 b so as to be rotatable, (d) a pulley 10 d connected to the motor 11, and (e) a belt 10 e that transmits driving force of the motor 11 from the pulley 10 d to the pulley 10 a.

The pulley 10 a is a rotator that rotates by the driving force of the motor 11, the power transmission member 12-1 is fixed to an end (a center of one of end surfaces) of the pulley 10 a, and the power transmission member 12-2 is fixed to the other end (a center of the other of the end surfaces) of the pulley 10 a.

Here, the driving force of the motor 11 is transmitted through the pulley 10 d and the belt 10 e to the pulley 10 a as a rotator in accordance to a belt driving manner. Alternatively, gears may be used instead of the pulleys 10 a and 10 d and engaged with each other, and the driving force of the motor 11 may be transmitted to the gear as a rotator that the power transmission members 12-1 and 12-2 are fixed to in accordance to a gear driving manner.

The motor 11 generates driving force in accordance with control by the controller 2, and thereby rotates a motor axis using the driving force. The driving force is transmitted to the pulley 10 a, and thereby the pulley 10 a rotates around a rotation axis Ax as a rotation center. The motor 11 is, for example, a stepping motor, a DC motor or the like.

The power transmission members 12-1 and 12-2 are members that rotate around the rotation axis Ax as a center of rotation by the driving force of the motor 11, respectively. In this embodiment, the power transmission members 12-1 and 12-2 are fixed to the pulley 10 a, and rotate around the rotation axis Ax (a center axis of the pulley 10 a having a circular plate shape) as a center of rotation together with the pulley 10 a.

In this embodiment, the power transmission members 12-1 and 12-2 have same shapes, and for example, as shown in FIG. 2 , each power transmission member 12-i (i=1, 2) includes an extension part 12 a that extends along a radial direction (i.e. a direction EDi in the figure) of the rotation axis Ax as a rotation center, and the extension part 12 a includes a guide hole 12 b along the radial direction. The power transmission members 12-1 and 12-2, and the pulley 10 a may be formed as a single member.

Each electromagnet 13-i is fixed to the power transmission member 12-i at a position facing the extension part 12 a through the aforementioned rotation axis Ax as a center (i.e. at an opposite position to the extension part 12 a); and when electric power is supplied to the electromagnet 13-i through lead wires from a power supply (not shown), the electromagnet 13-i generates electromagnetic force and absorbs the circular support member 14-i (specifically, the protrusion part 14 a) toward the electromagnet 13-i using the electromagnetic force. Here, the lead wires are arranged with predetermined lengths that do not interfere rotation of the motor 11.

Each circular support member 14-i is a member that provides tensile force to the wire 4-i connected to the load. In this embodiment, the circular support members 14-1 and 14-2 have same shapes, and each circular support member 14-i is a reel; and an end of the wire 4-i is fixed to the circular support member 14-i and the wire 4-i is wound on the circular support member 14-i. A main body (a part with a circular plate shape) of the circular support member 14-i is formed of resin, nonmagnetic metal or the like, for example.

Further, the lifting apparatus 1 includes a guide mechanism that supports the circular support member 14-i so as to enable the circular support member 14-i to slide in a predetermined range along a radial direction (i.e. a direction EDi in the figure) of the aforementioned rotation axis Ax.

In this embodiment, each of the guide mechanisms includes the guide hole 12 b in the power transmission member 12-i and the protrusion part 14 a in the circular support member 14-i, and the protrusion part 14 a is arranged in the guide hole 12 b. The protrusion part 14 a has a rectangular column shape, and is enabled to move while a side surface of the protrusion part 14 a contacts with an inner wall of the guide hole 12 b. Here, an end part 14 b of the protrusion part 14 a has a larger size than a height of the guide hole 12 b such that the circular support member 14-i does not fall from the power transmission member 12-i. For example, the protrusion part 14 a is formed as another member, a head end of it is arranged through the guide hole 12 b, and the protrusion part 14 a is fixed to a center of a main body (a part with a circular plate shape) of the circular support member 14-i using adhesion, a screw mechanism or the like. Further, the guide hole 12 b contacts with the protrusion part 14 a and thereby prohibits that the circular support member 14-i rotates around a center axis Aci of the circular support member 14-i as a center.

Each electromagnet 13-i forcibly arranges the circular support member 14-i using electromagnetic force at a position (hereinafter, called “stable operation position”) that the center axis Aci of the circular support member 14-i agrees with the aforementioned rotation axis Ax in this predetermined range.

FIGS. 5 and 6 show diagrams that explain arrangements of the circular support members 14-1 and 14-2 in the lifting apparatus 1 shown in FIGS. 2 to 4 . FIG. 5 shows a diagram that explains arrangement of the circular support members 14-1 and 14-2 in an ON status of the electromagnets 13-1 and 13-2. FIG. 6 shows a diagram that explains arrangement of the circular support members 14-1 and 14-2 in an OFF status of the electromagnets 13-1 and 13-2.

The controller 2 performs control of the motor 11 and performs turning on and off of electric power supply to the electromagnets 13-1 and 13-2 using a semiconductor switching element, relay, or the like, and thereby performs moving up or down of the load when required. In this embodiment, the controller 2 controls the electromagnets 13-1 and 13-2 in the same manner, and performs turning on and off of the electromagnets 13-1 and 13-2 in the same manner.

In this embodiment, if the power transmission members 12-1 and 12-2 are nonmagnetic members such as resin members, the protrusion parts 14 a of the circular support members 14-1 and 14-2 are magnetic members such as magnetic metal members, and the circular support member 14-i is located at a position other than the stable operation position in the aforementioned predetermined range, then when the electromagnet 13-i operates, adsorption power is generated to the circular support member 14-i (the protrusion part 14 a), and thereby the protrusion part 14 a of the circular support member 14-i slides along the guide hole 12 b and then contacts with an end of the guide hole 12 b and the circular support member 14-i is arranged at the stable operation position.

When the electromagnet 13-i is in an OFF status (i.e. in a power off status), the electromagnetic force of the electromagnet 13-i disappears, the circular support member 14-i slides in accordance with the aforementioned guide mechanism until torque applied to the motor 11 by the tensile force of the wires 4-1 and 4-2 due to the load becomes substantially zero, as shown in FIG. 6 . Specifically, until a direction from the aforementioned rotation axis Ax to a separation position P of the wire 4-i separated from the circular support member 14-i agrees with a direction of the tensile force of the wire 4-i, the tensile force of the wire 4-i causes the power transmission member 12-i to rotate and causes the circular support member 14-i to slide to a stopping position along the guide hole 12 b.

In this status (i.e. in the status that the circular support members 14-1 and 14-2 are located at the stopping positions), rotation torque due to the tensile force of the wires 4-1 and 4-2 (i.e. torque to rotate the pulley 10 a) does not occur, and therefore even if the aforementioned worm gear or the like is not installed, it is prevented that the motor 11 rotates in a power off status (i.e. that the wires 4-1 and 4-2 are pulled out due to gravity that applies the load).

Further, as shown in FIG. 6 , for example, if the electromagnets 13-1 and 13-2 are turned on to an ON status when the electromagnets 13-1 and 13-2 are in an OFF status and the circular support members 14-1 and 14-2 are in positions shown in FIG. 3 , then the circular support members 14-1 and 14-2 move to positions shown in FIG. 4 (stable operation positions). In this status, as shown in FIG. 5 , for example, the center axes Ac1 and Ac2 of the circular support members 14-1 and 14-2 agree with the aforementioned rotation axis Ax, and therefore, when the motor 11 rotates (i.e. when the pulley 10 a rotates), the center axes Ac1, and Ac2 of the circular support members 14-1 and 14-2 rotate without moving, and the driving force of the motor 11 causes rotation torque of the circular support members 14-1 and 14-2 and is transmitted to the wires 4-1 and 4-2, and thereby becomes the tensile force of the wires 4-1 and 4-2.

The following part explains operations of the lifting apparatus 1 in Embodiment 1.

(a) Wire Pulling-Out Operation

FIG. 7 shows a diagram that explains an operation (wire pulling-out operation) of the lifting apparatus 1 shown in FIGS. 2 to 4 . FIG. 8 shows a diagram that explains a maximum deviation length of the wire in the operation of the lifting apparatus 1 shown in FIG. 6 .

For example, as shown in FIG. 7 , when at the time 0, the motor 11 (the pulley 10 a) starts to rotate clockwisely as shown in the figure in a status of the stopping position, and the electromagnet 13-1 is turned on to an ON status, the center axis Ac1 of the circular support member 14-1 is rotationally turned around the rotation axis Ax as a rotation center along substantially opposite direction to an extension direction of the wire 4-1, and then at the time Ts, the circular support member 14-1 is arranged at the stable operation position. Afterward, the wire 4-1 is stably pulled out in proportion to a rotation angle of the motor 11 (specifically, a rotation angle of the pulley 10 a).

In this action, until the time Ts, the wire 4-1 is deviated to a reverse direction by a deviation length a. The maximum value amax of the deviation length a is expressed as the following formula.

amax=h+b−c=h+sqrt(h ² −d ²/4)−π*(d/2)*(90+arccos(d/(2*h)))/180

Here, as shown in FIG. 8 , b is a distance between the rotation axis Ax and the center axis Ac1 in a tensile direction of the wire 4-1 at the time 0 (the stopping position). h is a distance between the rotation axis Ax and the center axis Ac1 in a tensile direction of the wire 4-1 at the time Ts (the stable operation position). c is a length of a circular arc (i.e. a circular arc on a circumference of the circular support member 14-1) from the separation position pos1 of the wire 4-1 at the time 0 (the stopping position) to the separation position pos2 of the wire 4-1 at the time Ts (the stable operation position). Further, sqrt(x) indicates a square root of x, and d indicates a diameter of the circular support member 14-1.

Similarly, when at the time 0, the motor 11 (the pulley 10 a) starts to rotate clockwisely as shown in the figure in a status of the stopping position, and the electromagnet 13-2 is turned on to an ON status, the center axis Ac2 of the circular support member 14-2 is rotationally turned around the rotation axis Ax as a rotation center along substantially opposite direction to an extension direction of the wire 4-2, and then at the time Ts, the circular support member 14-2 is arranged at the stable operation position. Afterward, the wire 4-2 is stably pulled out in proportion to a rotation angle of the motor 11. In this action, until the time Ts, the wire 4-2 is deviated to a reverse direction by a deviation length a. The maximum value amax of the deviation length a is the aforementioned amax.

(b) Wire Pulling-In Operation

FIG. 9 shows a diagram that explains an operation (wire pulling-in operation) of the lifting apparatus 1 shown in FIGS. 2 to 4 .

For example, as shown in FIG. 9 , when at the time 0, the motor 11 (the pulley 10 a) starts to rotate counterclockwisely as shown in the figure in a status of the stopping position, and the electromagnet 13-1 is turned on to an ON status, after a short time, at the time Ts, the circular support member 14-1 is arranged at the stable operation position. Afterward, the wire 4-1 is stably pulled in in proportion to a rotation angle of the motor 11 (specifically, a rotation angle of the pulley 10 a).

When the circular support member 14-1 moves from the stopping position to the stable operation position, the maximum value amax of a deviation length a from the stopping position of the wire 4-1 is express as the following formula.

amax=h+b−c=h+sqrt(h ² −d ²/4)−π*(d/2)*(360−90−arccos(d/(2*h)))/180

Similarly, when at the time 0, the motor 11 (the pulley 10 a) starts to rotate counterclockwisely as shown in the figure from the stopping position, and the electromagnet 13-2 is turned on to an ON status, after a short time, at the time Ts, the circular support member 14-2 is arranged at the stable operation position. Afterward, the wire 4-2 is stably pulled in in proportion to a rotation angle of the motor 11 (specifically, a rotation angle of the pulley 10 a). The maximum value of the deviation length a from the stopping position of the wire 4-2 when the circular support member 14-2 moves from the stopping position to the stable operation position is the aforementioned amax.

(b) Operation in a Power Off Status

FIG. 10 shows a diagram that explains an operation in a power off status of the lifting apparatus 1 shown in FIGS. 2 to 4 when directions of the power transmission members 12-1 and 12-2 are in a predetermined first angle range. FIG. 11 shows a diagram that explains a maximum deviation length of the wire in an operation in a power off status of the lifting apparatus shown in FIG. 10 . FIG. 12 shows a diagram that explains an operation in a power off status of the lifting apparatus shown in FIGS. 2 to 4 when a direction of the power transmission member is in a predetermined second angle range.

In accordance with a direction of the power transmission member 12-1 in the power off status (i.e. an angle ω1 of a direction from the rotation axis Ax as a center to the center axis Ac1), the guide mechanism (the power transmission member 12-1 and the circular support member 14-1) takes different behaviors.

For example, as shown in FIG. 10 , if the angle ω1 is either equal to or less than 90 degrees, when at the time 0 the driving force of the motor 11 and the electromagnetic force of the electromagnet 13-1 disappear in a status that the circular support member 14-1 is located at the stable operation position, tensile force to the load rotates the circular support member 14-1 around the rotation axis Ax as a center (clockwisely in the figure) and causes the circular support member 14-1 to slide as mentioned, and thereby the circular support member 14-1 reaches the stopping position at the time Te and the rotation of the motor 11 (specifically, the rotation of the pulley 10 a) is stopped. Until the time Te, the wire 4-1 is pulled out by the deviation length x with the rotation of the motor 11. The maximum value xmax of the deviation length x is expressed as the following formula.

xmax=b+e=sqrt(h ² −d ²/4)+π*(d/2)*(270+arccos(d/(2*h)))/180

Here, as shown in FIG. 11 , b is a distance between the rotation axis Ax and the center axis Ac1 in a tensile direction of the wire 4-1 at the time Te (the stopping position). e is a length of a circular arc (i.e. a circular arc on a circumference of the circular support member 14-1) from the separation position pos1 of the wire 4-1 at the time 0 (the stable operation position) to the separation position pos2 of the wire 4-1 at the time Te (the stopping position).

Contrarily, as shown in FIG. 12 , for example, if the angle ω1 exceeds 90 degrees, when at the time 0 the driving force of the motor 11 and the electromagnetic force of the electromagnet 13-1 disappear in a status that the circular support member 14-1 is located at the stable operation position, tensile force to the load rotates the circular support member 14-1 around the rotation axis Ax as a center (counterclockwisely in the figure) and causes the circular support member 14-1 to slide as mentioned, and thereby the circular support member 14-1 reaches the stopping position at the time Te and the rotation of the motor 11 is stopped. Until the time Te, the wire 4-1 is pulled out by the deviation length y with the rotation of the motor 11. In this case, the deviation length y is relatively small because the rotation of the motor 11 is relatively small.

Similarly, in accordance with a direction of the power transmission member 12-2 in the power off status (i.e. an angle ω2 of a direction from the rotation axis Ax as a center to the center axis Ac2), the guide mechanism (the power transmission member 12-2 and the circular support member 14-2) takes different behaviors.

If the angle ω2 is either equal to or less than 90 degrees, when at the time 0 the driving force of the motor 11 and the electromagnetic force of the electromagnet 13-2 disappear in a status that the circular support member 14-2 is located at the stable operation position, tensile force to the load rotates the circular support member 14-2 around the rotation axis Ax as a center (clockwisely in the figure) and causes the circular support member 14-2 to slide as mentioned, and thereby the circular support member 14-2 reaches the stopping position at the time Te and the rotation of the motor 11 (specifically, the rotation of the pulley 10 a) is stopped. Until the time Te, the wire 4-2 is pulled out by the deviation length x with the rotation of the motor 11. The maximum value of the deviation length x is the aforementioned xmax.

Contrarily, if the angle ω2 exceeds 90 degrees, when at the time 0 the driving force of the motor 11 and the electromagnetic force of the electromagnet 13-2 disappear in a status that the circular support member 14-2 is located at the stable operation position, tensile force to the load rotates the circular support member 14-2 around the rotation axis Ax as a center (counterclockwisely in the figure) and causes the circular support member 14-2 to slide as mentioned, and thereby the circular support member 14-2 reaches the stopping position at the time Te and the rotation of the motor 11 is stopped. Until the time Te, the wire 4-2 is pulled out by the deviation length y with the rotation of the motor 11. In this case, the deviation length y is relatively small because the rotation of the motor 11 is relatively small.

As mentioned, in Embodiment 1, the lifting apparatus 1 includes the motor 11, the circular support members 14-1 and 14-2, the power transmission members 12-1 and 12-2, the guide mechanisms, and the electromagnets 13-1 and 13-2. The circular support members 14-1 and 14-2 provide tensile forces to the wires 4-1 and 4-2 connected to a load. The power transmission members 12-1 and 12-2 rotate around the rotation axis Ax as a center of rotation by driving force of the motor 11. The guide mechanisms support the circular support members 14-1 and 14-2 so as to enable the circular support members 14-1 and 14-2 to slide in a predetermined ranges along a radial direction of the rotation axis Ax, respectively. The electromagnets 13-1 and 13-2 forcibly arrange the circular support members 14-1 and 14-2 using electromagnetic force at a position that the center axes Ac1 and Ac2 of the circular support members 14-1 and 14-2 agree with the rotation axis Ax in the predetermined ranges.

Consequently, the lifting apparatus 1 restrains backstop in a power off status with a relatively uncomplicated and compact configuration.

Embodiment 2

FIG. 13 shows a front view diagram that indicates a configuration of a lifting apparatus in Embodiment 2. FIG. 14 shows a diagram that explains an operation in a power off status of the lifting apparatus in Embodiment 2.

In Embodiment 1, an angle θe is 180 degrees where ee is an angle between a direction ED1 (from the rotation axis Ax) of the guide mechanism including the power transmission member 12-1 and the circular support member 14-1 (i.e. a movement direction of the wire 4-1) and a direction ED2 (from the rotation axis Ax) of the guide mechanism including the power transmission member 12-2 and the circular support member 14-2 (i.e. a movement direction of the wire 4-2). However, in Embodiment 2, as shown in FIGS. 13 and 14 , this angle θe is an angle other than 180 degrees.

Other parts of the configuration of the lifting apparatus in Embodiment 2 are identical or similar to those in Embodiment 1, and therefore not explained here.

The following part explains operations of the lifting apparatus 1 in Embodiment 2.

A wire pulling-out action and a wire pulling-in action of the lifting apparatus 1 in Embodiment 2 are taken in the movement directions (ED1 and ED2) of the wires 4-1 and 4-2 between which an angle is ee (other than 180 degrees), as shown in FIG. 13 , for example.

Further, in a behavior when power off occurs of the lifting apparatus 1 in Embodiment 2, as shown in FIG. 14 , for example, the wires 4-1 and 4-2 are pulled out as well as in Embodiment 1 in the movement directions (ED1 and ED2) of the wires 4-1 and 4-2 between which an angle is ee (other than 180 degrees).

Other parts of the behaviors of the lifting apparatus in Embodiment 2 are identical or similar to those in Embodiment 1, and therefore not explained here.

As mentioned, in Embodiment 2, the angle θe between the moving directions of the two wires 4-1 and 4-2 may not be 180 degrees.

It should be understood that various changes and modifications to the embodiments described herein will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the spirit and scope of the present subject matter and without diminishing its intended advantages. It is therefore intended that such changes and modifications be covered by the appended claims.

For example, in the aforementioned embodiments, the lifting apparatus 1 is used in the sheet storage apparatus, in which the sheet loading unit 3 a (and loaded sheets) are a load of the lifting apparatus 1. Alternatively, the lifting apparatus 1 may move up and down another load of another type. For example, the lifting apparatus 1 may be applied in a reel device for a fishing line or a kite string or a winch for construction machinery, an elevator or the like.

Further, in the aforementioned embodiments, the wire 4-i may have a ring shape (i.e. endless wire) and a driving pulley may be used as the circular support member. 

What is claimed is:
 1. A lifting apparatus that causes a load to move up and down, comprising: a motor; a first circular support member configured to provide tensile force to a first wire connected to the load; a first power transmission member configured to rotate around a rotation axis as a center of rotation by driving force of the motor; a first guide mechanism configured to support the first circular support member so as to enable the first circular support member to slide in a predetermined first range along a radial direction of the rotation axis; a first electromagnet configured to forcibly arrange the first circular support member using electromagnetic force at a position that a center axis of the first circular support member agrees with the rotation axis in the predetermined first range; a second circular support member configured to provide tensile force to a second wire connected to the load; a second power transmission member configured to rotate around the rotation axis as a center of rotation by driving force of the motor; a second guide mechanism configured to support the second circular support member so as to enable the second circular support member to slide in a predetermined second range along a radial direction of the rotation axis; and a second electromagnet configured to forcibly arrange the second circular support member using electromagnetic force at a position that a center axis of the second circular support member agrees with the rotation axis in the predetermined second range.
 2. The lifting apparatus according to claim 1, further comprising a rotator configured to rotate by driving force of the motor; wherein the first power transmission member is fixed at an end of the rotator; and the second power transmission member is fixed at another end of the rotator.
 3. The lifting apparatus according to claim 1, wherein the first and second power transmission members comprise guide holes along the radial directions, respectively; the first and second circular support members comprises protrusion parts to be arranged in the guide holes, respectively; and the first and second guide mechanism comprises the guide holes and the protrusion parts, respectively.
 4. The lifting apparatus according to claim 3, wherein the first and second power transmission members are nonmagnetic members; and the protrusion parts are magnetic members.
 5. The lifting apparatus according to claim 1, wherein in a power off status, the electromagnetic force of the first and second electromagnets disappears, and the first and second circular support members slide in accordance with the first and second guide mechanisms until torque applied to the motor by the tensile force of the first and second wires due to the load becomes substantially zero.
 6. The lifting apparatus according to claim 1, wherein an angle between a direction of the first guide mechanism and a direction of the second guide mechanism is a predetermined angle other than 180 degrees.
 7. A sheet storage apparatus, comprising: a lifting apparatus; and a sheet loading unit configured to be caused to move up and down by the lifting apparatus; wherein the lifting apparatus comprises: a motor; a first circular support member configured to provide tensile force to a first wire connected to the sheet loading unit; a first power transmission member configured to rotate around a rotation axis as a center of rotation by driving force of the motor; a first guide mechanism configured to support the first circular support member so as to enable the first circular support member to slide in a predetermined first range along a radial direction of the rotation axis; a first electromagnet configured to forcibly arrange the first circular support member using electromagnetic force at a position that a center axis of the first circular support member agrees with the rotation axis in the predetermined first range; a second circular support member configured to provide tensile force to a second wire connected to the sheet loading unit; a second power transmission member configured to rotate around the rotation axis as a center of rotation by driving force of the motor; a second guide mechanism configured to support the second circular support member so as to enable the second circular support member to slide in a predetermined second range along a radial direction of the rotation axis; and a second electromagnet configured to forcibly arrange the second circular support member using electromagnetic force at a position that a center axis of the second circular support member agrees with the rotation axis in the predetermined second range. 